The objective of this study is to further define the pathology of dengue hemorrhagic fever at the ultrastructural level and to search for viral or related structure in the tissue and cells of living or dead host suffered from this form of dengue infection. In addition, an attempt to localize dengue virus antigen as well as to demonstrate the fixation, if any of immunoglobin and complement in the tissue of these subjects by immunofluorescent methods will be made.